To talk more about those opponents and what's happening on the campaign trail, we turn now to NPR's Cokie Roberts, who joins us most Mondays. Good morning, Cokie.

COKIE ROBERTS, BYLINE: Hi, Renee.

MONTAGNE: So let's - it looks like there's one less rival in the Republican contest, now that former Utah Governor Jon Huntsman is expected to drop out today and throw his support to Mitt Romney. Let's talk about the likely effect on the rest of the contenders.

ROBERTS: Well, I'm not sure he's going to have much of an effect on the rest of the contenders. Look, Jon Huntsman was just simply not getting anywhere. He didn't do well enough in New Hampshire, where he had put all of his energy, to really carry on. And he's getting out before yet another debate tonight, which seems wise. And it allows his backers and, to some extent, his staff, to get on the side of the frontrunner - which will help them in the long run.

I think that his own endorsement of Romney is not likely to mean very much. The Democratic National Committee is already touting all of Huntsman's criticisms of Romney as not trustworthy, not electable. Huntsman's campaign took all of that off of their website last night.

But to show how little endorsements really matter these days, Huntsman gets out the same day that he was endorsed by South Carolina's biggest newspaper. I just don't think that they signify very much in modern politics.

Now, Romney has had the advantage of the governor, Nikki Haley, sort of validating him and going around the state with him, but she's not terribly popular. Ron Paul is coming into South Carolina today to receive the endorsement of Tea Partier Congressman Tom Davis. But again, it's not likely to really matter for him.

MONTAGNE: Well, as we just heard from Don, there was another endorsement this weekend that in the past certainly would have been important, and that was the one for Rick Santorum by religious conservative leaders who were meeting in Texas. How much then, in fact, might this really mean?

ROBERTS: Well, I think that, again, in past years it would have been huge. If there were still the force behind a Jerry Falwell-type preacher, then that would have really been an enormous endorsement for Santorum. And obviously it's helpful to him, as we just heard in Gonyea's piece, but it's not big enough.

And I mean there's just nobody who is swaying these voters. And the other conservatives, the other people who are positioning themselves as the not-Romney candidate, Rick Perry and Newt Gingrich, are not going anywhere. They're not getting out.

MONTAGNE: So what are we learning, Cokie, about the Republican Party in the primaries so far? I mean, there's so much talk about the polarized politics in this country. Can a candidate win the Republican primary vote and still bring in Independent voters in the general election?

ROBERTS: Well, of course that's always the danger, that the things a candidate says to win over the true believers turn off everyone else. But this has been such a strange campaign. In Iowa, the independents went overwhelmingly for Ron Paul. In New Hampshire where Independents are a plurality of the voters, they split their votes among Paul, Huntsman, and Romney.

So they haven't been turned off by Romney, but his opponents' attacks against him have been these attacks about his tenure at Bain Capital that are meant to appeal to lower-income, out-of-work whites in South Carolina, but it could also appeal to those same folk in the general election, and they could decide to go Democratic as a result of it. So that could be a true problem for him, not because of what he's done to appeal to the base, but how his opponents have characterized him.

Now those opponents, mainly Gingrich and Perry, have gotten a lot of heat from inside the party, but they counter that it's better to launch these attacks now rather than later. We'll see, Renee, you know, Democrats can use them - use those Republicans saying these things later in the campaign.

Santorum's chosen to go after Romney's record as governor of Massachusetts and health care there, and used it to paint him as unelectable. If voters believe him, that's smart, because Romney's biggest strength so far has been that he is the guy who can beat Barack Obama.

But I think the really - only significant damage that Romney has done by appealing to his base is to drive away Hispanic voters by taking a harder and harder line on immigration, and it is instructive that he has up now, in Florida - which is the next primary up after this one - a Spanish language ad. So he's already beginning to try to cover that ground.